Abstract: A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; 5 ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are 10 retrieved and used in combination.

Abstract: The invention relates to a method for detecting the pre-ignition of an internal combustion engine comprising: integrating all instantaneous angular accelerations in a feature window to acquire integral values, and judging whether the internal combustion engine is pre-ignited according to the integral values and an pre-ignition threshold in a detection window; the feature window is an angle range corresponding to a top dead center of the compression stroke of the internal combustion engine to 3-5 consecutive signal teeth backward from the top dead center along the rotating direction of a crankshaft; the instantaneous angular accelerations correspond to the signal teeth in the feature window in a one-to-one manner.

Abstract: Described is a current sensor comprising: a main resistive branch having a target device coupled to a load at a first node; a replica resistive branch having a replica device which is a replica of the target device, the replica device coupled to a current digital to analog converter (DAC) at a second node; and an analog to digital converter (ADC) coupled directly or indirectly to the first and second nodes, the ADC to generate an output coupled to the current DAC.

Abstract: A single-cylinder internal combustion engine includes a knock sensor mounted to apart other than a cylinder block to detect knocking. The engine includes a crankcase, a cylinder block, and a cylinder head connected by a bolt. A boss to mount the knock sensor is provided on the crankcase. A center of the boss is positioned on a same side of a cylinder axis as the bolt, when viewed in an axial direction of the boss.

Abstract: In a method for recognizing knocking of an internal combustion engine, solid-borne sound signals are measured and solid-borne sound features are recovered from the measured sound signals. A peak pressure for a combustion event of the internal combustion engine is estimated from the solid-borne sound features, and the estimated peak pressure is compared with a knock recognition threshold, knocking of the internal combustion engine being recognized when the knock recognition threshold is exceeded by the estimated peak pressure.

Abstract: In a knock control device of an internal combustion engine equipped with a control unit which updates a background level based on an output signal from a knock sensor and detects the generation of a knock by comparing a variation of the background level with a knock determination value, a determination as to whether the knock is generated is performed by ((variation of first filter value of peak hold value)>((1?filter coefficient)/(1+filter coefficient)×(predetermined value larger than maximum value of variation of peak hold value in case where knock is not generated))).

Abstract: An electronic control unit (ECU), for use with an internal combustion engine, determines whether an abnormal combustion has occurred in the engine. The ECU uses a sensor signal amplifier to amplify a sensor signal from a sensor by changing an amplification power of the sensor signal and an A/D converter to convert the sensor signal amplified to a digital signal (i.e., a digitized sensor signal). The ECU uses an abnormal combustion detector to determine whether an abnormal combustion has occurred based on a characteristic of a waveform of the digitized sensor signal, and performs an abnormal combustion prevention control to prevent the abnormal combustion when an abnormal combustion is detected. An amplification controller is used to set the amplification power of the sensor signal amplifier based on the amplitude of the digitized sensor signal and a determination result of the abnormal combustion by the abnormal combustion detector.

Abstract: A smoke alarm comprises smoke detection circuitry for detecting smoke and generating a detection signal responsive thereto. Proximity detection circuitry generates a proximity detection signal responsive to detection of an object within in a selected distance of the smoke alarm. Alarm generation circuitry generates an audible alarm responsive to the detection signal. The audible alarm may be deactivated for a predetermined period of time responsive to at least one proximity detection signal.

Abstract: A frequency spectrum analyzing apparatus for performing a frequency spectrum analysis with respect to a detected value of an operating parameter of an internal combustion engine in synchronism with rotation of the engine, is provided. The operating parameter is sampled at predetermined time intervals, and a sampled value is converted to a digital value. Intensities of first and second elements are calculated with respect to a predetermined number of the sampled values. The first elements and second elements respectively correspond to a plurality of frequency components contained in the detected value, and a phase of the second element differs from a phase of the first element by 90 degrees. Frequency component intensities corresponding to the plurality of frequency components are calculated in synchronism with rotation of the engine, using the first element intensities and the second element intensities.

Abstract: A method and a system is disclosed for determining RON and/or MON values from constant volume combustion chamber apparatuses capable of producing pressure versus time combustion profiles having a fast combustion region and a slow combustion region, where data from the two regions is used to compute RON and/or MON values for light distillate fluid samples using a series expansion equation.

Abstract: A detector circuit for detecting the presence of a remote capacitive sensor having at least two terminals connected via a protection circuit that includes one or more capacitors, the detector circuit comprising: a current supply for changing the charge on the sensor and the protection circuit, a detector for measuring the voltage on one or more of the terminals; wherein the presence of the sensor is determined by changing the charge on the capacitive sensor and the one or more capacitors of the protection circuit in a predetermined manner such that the voltage measurement on the one or more terminals when the sensor is present is significantly different than when the sensor is absent.

Abstract: An outer electrode projects from an opening, which is formed in an upper inner wall of a fuel passage, into the fuel passage. The fuel passage is adapted to conduct fuel generally in a horizontal direction. The outer electrode includes a fuel chamber in an inside of the outer electrode. An inner electrode is placed in the fuel chamber. A sensing circuit senses an alcohol concentration of the fuel based on an electrical property between the outer electrode and the inner electrode and a fuel temperature, which is sensed with a thermistor. The outer electrode includes a blocking portion and communication holes. The blocking portion limits intrusion of air bubbles, which flow along the upper inner wall of the fuel passage, into the communication holes.

Abstract: An abnormal combustion detection method for spark-ignition internal-combustion engines, from combustion indicator distribution modelling is disclosed. At least one combustion indicator such as CA10 is determined. The distribution of N values of this indicator, acquired over N cycles preceding the cycle in progress, is modelled by determining coefficients of a theoretical distribution law. Modelling is repeated by removing extreme values from among the N values or for various working points of the engine, to obtain an evolution of the coefficients. At least one parameter characterizing evolution of at least one of these coefficients is determined. The start of an abnormal combustion is detected by comparing the parameter with a predetermined threshold, and the course of the abnormal combustion detected in the combustion chamber is controlled.

Abstract: In order to obtain a knock detection device of an internal combustion engine which satisfies two objects of following capability and separation from a continuous knock generation state, when a background level is calculated by ((current background level)=(filter coefficient)×(previous background level)+(1?filter coefficient)×(output signal from knock sensor)), updating quantity of the background level is limited by ((1?filter coefficient)×(value not lower than maximum value of output signal from knock sensor at time when knock is not generated)).

Abstract: A knock detection system for an engine includes an intensity module, a knock threshold module, and a detection module. The intensity module determines an engine vibration intensity during a first period of engine operation. The knock threshold module determines a knock threshold based on an ethanol concentration in a fuel supplied to the engine. The detection module determines whether engine knock has occurred during the first period by comparing the knock threshold and the engine vibration intensity.

Abstract: An apparatus and method for measuring a Signal-to-Interference-plus-Noise Ratio (SINR) by controlling a residual gain in a high speed packet access system are provided. The apparatus includes a gain controller for measuring an intensity of a signal outputted from a residual gain controller, for outputting a gain control signal for controlling a gain of an interval of a preset gain resolution of a radio frequency integrated circuit according to the intensity of measured signal, and for outputting a residual gain value for controlling a residual gain less than the preset gain resolution, wherein the radio frequency integrated circuit gain-controls a signal inputted according to the gain control signal, and the residual gain controller multiplies the gain-controlled signal by the residual gain value to compensate the residual gain.

Abstract: An apparatus for furnishing an amplified sensor signal of a knock sensor, encompassing an analog amplifier for amplifying the sensor signal in accordance with a first definable gain factor; an analog/digital converter for digitizing the amplified sensor signal into a digitized sensor signal; a digital amplifier for amplifying the digitized sensor signal in accordance with a second definable gain factor; and a control unit in order to furnish the first and the second gain factor as a function of a baseline sound level of the sensor signal, the baseline sound level corresponding to the component of the solid-borne sound signal generated in normal operation without knocking.

Abstract: A single-cylinder internal combustion engine includes a knock sensor mounted thereto to suppress a temperature increase of the knock sensor and at the same time detect knocking with high accuracy. The engine includes a cylinder block having a cylinder provided therein, and a cylinder head connected to the cylinder block. On a surface of the cylinder block and the cylinder head, one or more fins protruding from the surface are provided. On the surface of the cylinder block, a sensor mounting boss protruding from the surface and being continuous with a portion of the one or more fins is provided. A knock sensor arranged to detect knocking is mounted to the sensor mounting boss.

Abstract: In a single-cylinder internal combustion engine fitted with a knock sensor, a temperature increase of the knock sensor is suppressed and prevented and the reliability of the knock sensor is improved. The engine includes a crankcase accommodating a crankshaft, a cylinder block connected to the crankcase and including a cylinder provided therein, a cylinder head connected to the cylinder block, a sensor mounting boss provided on the cylinder block, a knock sensor arranged to detect knocking and mounted to the boss, a fan to guide air to at least the sensor mounting boss, and an air shroud.

Abstract: In the field of knock detection in a combustion engine, a method and a device detects and controls the knock by adapting the gain of an amplifier which amplifies the knock sensor signal. The gain of the amplifier is adapted based on analysis of a set of samples from the knock sensor so that the amplification of the knock sensor signal across the entire measuring window is optimum and the complete ADC evaluation range can be utilized better.

Abstract: For the processing of a knock sensor signal during the detection of knocking in a combustion engine, in order to allow for inexpensively designed, efficient, and accurate bandpass filtering, a signal processing device (10) has an analog filter (20), a sigma-delta modulator (30) designed for analog-digital conversion, a CIC filter (40) designed to decimate the sampling rate, and a digital filter (50).

Abstract: An object is to provide an abnormal combustion determining apparatus for an internal combustion engine that can identify a major factor causing an oil to flow into a cylinder. The abnormal combustion determining apparatus for the internal combustion engine that includes a plurality of cylinders detects, for each cylinder, a cylinder in which abnormal combustion has occurred. The cylinder in which the abnormal combustion has occurred, and a history of load applied during an operation are stored in memory. It is determined whether or not the cylinder in which the abnormal combustion has occurred and which is stored in memory, is a specific cylinder. It is determined whether or not load present in the history stored in memory and used prior to the occurrence of the abnormal combustion is higher than a threshold value.

Abstract: An engine ECU executes a program including: detecting a magnitude of vibration of an engine; detecting a vibration waveform of the engine based on the magnitude; calculating a correlation coefficient, in the case where the engine speed is smaller than a threshold value, using the sum of values each determined by subtracting a positive reference value from a magnitude of a knock waveform model, as an area of the knock waveform model and, calculating the correlation coefficient, in the case where the engine speed is not smaller than the threshold value, using the area of the whole knock waveform model; and determining whether or not knocking has occurred using the correlation coefficient. The correlation coefficient is calculated by dividing by the area the sum of differences that are each the difference between the magnitude on the vibration waveform and the magnitude on the knock waveform model.

Abstract: This invention relates to a method for knock detection in a combustion engine, in which combustion is controlled by a control unit (2), which comprises the steps of, a) obtaining at least one sensor signal (4, 4?) carrying information of knock intensity related within a combustion chamber of the combustion engine (1); (b) processing the sensor signal (4, 4?) to obtain a knock intensity related detection variable (z1), (c) using said detection variable (z1) in said control unit (2) arranged to avoid a knocking condition in said combustion engine (1), if the value (z1) of said detection variable indicates knock when compared with a threshold value (T) wherein using two different computations/processes for said processing (5, 6) of the at least one sensor signal (4, 4?) to obtain two separate sub-values (y1, y2), and thereafter combining said sub-values (y1, y2) to obtain said detection variable (z1).

Abstract: An object is to provide an abnormal combustion determining apparatus for an internal combustion engine that can identify a major factor causing an oil to flow into a cylinder. The abnormal combustion determining apparatus for the internal combustion engine that includes a plurality of cylinders detects, for each cylinder, a cylinder in which abnormal combustion has occurred. The cylinder in which the abnormal combustion has occurred, and a history of load applied during an operation are stored in memory. It is determined whether or not the cylinder in which the abnormal combustion has occurred and which is stored in memory, is a specific cylinder. It is determined whether or not load present in the history stored in memory and used prior to the occurrence of the abnormal combustion is higher than a threshold value.

Abstract: An engine ECU executes a program including calculating a correlation coefficient by dividing the sum of respective absolute values, which are each a difference between a magnitude in an engine vibration waveform and a magnitude in a knock waveform model for every crank angle, by an area corresponding to magnitudes equal to or larger than a positive reference value in the knock waveform model, and determining whether or not knocking has occurred based on the correlation coefficient.

Abstract: The invention relates to a method for determining the ignitability of a fuel, in particular a self-igniting fuel, based on the ignition delay of the fuel during the combustion in a test engine. According to the invention, the ignition delay is determined from the combustion curve and/or the heat curve.

Abstract: Methods and systems are provided for identifying and differentiating knock and pre-ignition using a plurality of knock sensors distributed along an engine block. By dynamically adjusting cylinder-specific assignment of the knock sensors for knock detection and pre-ignition detection based on operating conditions of each cylinder, knock and pre-ignition is more reliably identified and distinguished.

Abstract: An engine ECU executes a program including the steps of: calculating a coefficient of correlation K in accordance with a result of comparing a waveform of a vibration of a frequency band including a resonance frequency of an engine with a knock waveform model previously created as a waveform of a vibration caused when the engine knocks; calculating a knock intensity N from an intensity of a vibration of a frequency band excluding the resonance frequency of the engine; if knock intensity N is larger than a reference value and coefficient of correlation K is larger than a threshold value, determining that the engine knocks; and if knock intensity N is smaller than the reference value and/or coefficient of correlation K is smaller than the threshold value, determining that the engine does not knock.

Abstract: Out of synthesized waveforms of vibrations in a first frequency band A to a third frequency band C, a knock magnitude N is calculated by using a portion ? having an integrated value greater than a reference magnitude in a knock region but not using a portion having an integrated value greater than the reference magnitude out of the knock region (i.e., a region obtained by excluding the knock region from a knock detecting gate). In a case where knock magnitude N is greater than a determination value V(KX), it is determined that knocking occurs. In contrast, in a case where knock magnitude N is not greater than determination value V(KX), it is determined that no knocking occurs.

Abstract: An apparatus for furnishing an amplified sensor signal of a knock sensor, encompassing an analog amplifier for amplifying the sensor signal in accordance with a first definable gain factor; an analog/digital converter for digitizing the amplified sensor signal into a digitized sensor signal; a digital amplifier for amplifying the digitized sensor signal in accordance with a second definable gain factor; and a control unit in order to furnish the first and the second gain factor as a function of a baseline sound level of the sensor signal, the baseline sound level corresponding to the component of the solid-borne sound signal generated in normal operation without knocking.

Abstract: For the processing of a knock sensor signal during the detection of knocking in a combustion engine, in order to allow for inexpensively designed, efficient, and accurate bandpass filtering, a signal processing device (10) has an analog filter (20), a sigma-delta modulator (30) designed for analog-digital conversion, a CIC filter (40) designed to decimate the sampling rate, and a digital filter (50).

Abstract: An engine ECU executes a program including a step of setting a search range of the crank angle of a peak value P that is the largest integrated value in a vibration waveform of an engine detected by calculating integrated values that are integrals of output voltage values of a knock sensor for every five degrees of a crank angle such that the search range may include the crank angle increasing with increase in engine speed NE, and a step of detecting the crank angle of the largest integrated value in the search range, and setting the detected crank angle as the crank angle of peak value P in the vibration waveform. At the crank angle based on the crank angle of peak value P, the vibration waveform is compared with a knock waveform model.

Abstract: An engine ECU executes a program including calculating a correlation coefficient by dividing the sum of respective absolute values, which are each a difference between a magnitude in an engine vibration waveform and a magnitude in a knock waveform model for every crank angle, by an area corresponding to magnitudes equal to or larger than a positive reference value in the knock waveform model, and determining whether or not knocking has occurred based on the correlation coefficient.

Abstract: An engine ECU executes a program including: the step of increasing a determination value by a correction amount if the number of knock intensities not lower than the determination value is not smaller than a threshold value among knock intensities of a plurality of predetermined number of continuous ignition cycles; and the step of increasing the determination value by a correction amount if the number of knock intensities not smaller than the determination value is not smaller than a threshold value, among knock intensities of a plurality of ignition cycles satisfying the condition that a coefficient of correlation calculated by comparing a vibration waveform and a knock waveform model is not smaller than a threshold value, of the knock intensities of a plurality of predetermined continuous ignition cycles.

Abstract: An engine ECU executes: calculating 15-degrees integrated value integrating vibration intensity for each of six crank angle ranges; detecting an amount of change in the 15-degrees integrated value between ignition cycles; specifying two ranges having larger amounts of change; specifying a crank angle having intensity larger than that of a neighboring crank angle in a search range determined to be the same as the specified ranges; calculating a coefficient of correlation K corresponding to a difference between a vibration waveform and a knock waveform model while the specified crank angle is matched with a timing at which intensity peaks in the knock waveform model; and, if the coefficient of correlation K is larger than a threshold value K(0), determining that knock has occurred.

Abstract: An engine ECU executes a program including a step of calculating intensity values LOG(V) based on signals transmitted from a knock sensor; a step of deciding a maximum value V(MAX) in frequency distribution of intensity values LOG(V) for N cycles (N is a natural number); a step of calculating a knock determination level V(KD) based on the frequency distribution; a step of, when the knock determination level V(KD) is smaller than the maximum value V(MAX), removing V(MAX) from the frequency distribution; and a step of counting the total frequency of removed maximum values V(MAX) as knock occupancy KC. Maximum values V(MAX) are removed until the knock determination level V(KD) and the maximum value V(MAX) coincide, and the knock determination level V(KD) is recalculated.

Abstract: A device having at least one screw plug for screwing into a first tapped hole of a housing or housing part of the device, the at least one screw plug including a device for sealing, such as a sealing ring, for the connection to the housing in a manner forming a seal, e.g., against the escape of oil. Introduced into the screw plug is a second tapped hole by which a sensor is releasably connectable, e.g., is able to be screwed in. The screw plug includes an end stop for conducting acoustical waves and for the simultaneous mechanical limit for screwing in the screw plug.

Abstract: A knock sensor includes: a base made up of a flange portion, and a tube portion; a sensor main body including a piezoelectric element that is fitted over an outer peripheral portion of the tube portion; and a stopper ring that is fitted over the outer peripheral portion of the tube portion and cooperates with the flange portion to clamp the sensor main body, a groove being formed on the outer peripheral surface of the tube portion, and the knock sensor being fixed by driving a pressing jig into an outer peripheral surface of the stopper ring to plastically deform the stopper ring and press a protruding portion into the groove, wherein: an axial length of a recess portion that is formed simultaneously on the outer peripheral surface of the stopper ring when the protruding portion is formed is longer than an axial length of the groove.

Abstract: A three-wafer channel or column structure for a fluid analyzer. The structure may have a support member, membrane, or support wafer containing heaters and interactive elements. The membrane may have a channel of one wafer facing the interactive element side and a space of another wafer facing the other side. The membrane may have perforations to equalize the pressures on both sides of the membrane. A detector in the membrane may have exposure to both the channel and space for good sensitivity, as the sample may be on both sides of the membrane. The wafers may be bonded with a thin film of non-flowing viscous material. Capillaries may be attached to an inlet and outlet of the channel and be parallel to an elongated dimension of the channel.

Abstract: An engine knock detection system for a vehicle engine includes a controller receiving an input indicative of strain applied to an engine component and an output for providing a signal indicative of engine knock. A sensor may be associated with the engine that measures operating parameters of the engine (i.e., strain, for example) to allow the controller to detect and identify engine knock. The sensor may include a Surface-Acoustic Wave (SAW) sensor, such as, for example, a double-SAW sensor that concurrently detects engine torque.

Abstract: An engine ECU executes a program including a step of calculating intensity values LOG(V), a step of detecting vibration waveforms, a step of calculating a correlation coefficient K based on vibration waveforms, a step of preparing frequency distribution of intensity values LOG(V) smaller than a threshold V(1) and intensity values LOG(V) in an ignition cycle where correlation coefficient K is larger than a threshold K(1), a step of calculating a knock determination level V(KD) based on a median V(50) and a standard deviation ? of intensity values LOG(V), and a step of counting the number of intensity values LOG(V) larger than knock determination level V(KD) as the number of times that knocking has occurred.

Abstract: An engine ECU executes a program including a step of calculating intensity values LOG(V) based on signals transmitted from a knock sensor; a step of deciding a maximum value V(MAX) in frequency distribution of intensity values LOG(V) for N cycles (N is a natural number); a step of calculating a knock determination level V(KD) based on the frequency distribution; a step of, when the knock determination level V(KD) is smaller than the maximum value V(MAX), removing V(MAX) from the frequency distribution; and a step of counting the total frequency of removed maximum values V(MAX) as knock occupancy KC. Maximum values V(MAX) are removed until the knock determination level V(KD) and the maximum value V(MAX) coincide, and the knock determination level V(KD) is recalculated.

Abstract: A motorcycle engine includes a crankcase housing a crankshaft, and a transmission unit therein, a cylinder block disposed above the crankcase, a cylinder head disposed above the cylinder block, and an intake system arranged behind the cylinder head, and a knock sensor arranged on an upper surface of the crankcase. The knock sensor is arranged behind the cylinder head, and disposed between the intake system and the cylinder block, such that the knock sensor does not restrict arrangement of additional functional parts of the engine on an upper surface of the crankcase. The knock sensor is substantially surrounded and protected by the intake system, the cylinder head, the cylinder block and the crankcase.

Abstract: An engine ECU executes a program including: the step (S222) of increasing a determination value V(J) by a correction amount A(3) if the number of knock intensities N not lower than the determination value V(J) is not smaller than a threshold value B(1) (YES at S220) among knock intensities N of a plurality of predetermined number of continuous ignition cycles; and the step (S232) of increasing the determination value V(J) by a correction amount A(5) if the number of knock intensities N not smaller than the determination value V(J) is not smaller than a threshold value B(3) (YES at S230), among knock intensities N of a plurality of ignition cycles satisfying the condition that a coefficient of correlation K calculated by comparing a vibration waveform and a knock waveform model is not smaller than a threshold value K(1), of the knock intensities of a plurality of predetermined continuous ignition cycles.

Abstract: An internal combustion engine control apparatus controls an air intake mass at an idle state after a start of an internal combustion engine based on a correction mass of the air intake mass calculated based on a desired value of the air intake mass and a measured value of the air intake mass. The air intake mass is controlled based on an idle speed control variable corresponding to the desired value of the air intake mass, and an idle speed control variable at when the correction mass is calculated. Each idle speed control variable includes a degree of a throttle opening or a degree of an idle speed control valve opening.

Abstract: An engine knock detection system for a vehicle engine includes a controller receiving an input indicative of strain applied to an engine component and an output for providing a signal indicative of engine knock. A sensor may be associated with the engine that measures operating parameters of the engine (i.e., strain, for example) to allow the controller to detect and identify engine knock. The sensor may include a Surface-Acoustic Wave (SAW) sensor, such as, for example, a double-SAW sensor that concurrently detects engine torque.

Abstract: An engine ECU executes a program including a step of calculating intensity values LOG(V) based on signals transmitted from a knock sensor; a step of deciding a maximum value V(MAX) in frequency distribution of intensity values LOG(V) for N cycles (N is a natural number); a step of calculating a knock determination level V(KD) based on the frequency distribution; a step of, when the knock determination level V(KD) is smaller than the maximum value V(MAX), removing V(MAX) from the frequency distribution; and a step of counting the total frequency of removed maximum values V(MAX) as knock occupancy KC. Maximum values V(MAX) are removed until the knock determination level V(KD) and the maximum value V(MAX) coincide, and the knock determination level V(KD) is recalculated.

Abstract: The automated fault diagnostic system operates on engine-compressor sets with one vibration sensor per sub-group of engine cylinders and one sensor per compressor cylinder. Vibration signals linked to crankshaft phase angle windows (“VT”) mark various engine events and compressor events. In data-acquisition-learning mode, VT is stored for each engine and compressor event per operating load condition, statistical process control (SPC) theory identifies alarm threshold bands. Operator input-overrides are permitted. If no baseline data is stored, the system automatically enters the learn mode. To monitor, current VT are obtained and current load condition is matched to the earlier load set and alarms issue linking predetermined engine or compressor event to the over-under VT. Baseline data, SPC analysis, alarms and monitoring are set for crankcase flow, engine cylinder exhaust temperatures, ignition system diagnostic messages. Compressor performance alarms use suction and discharge temperatures and pressures.

Abstract: In an ignition system that includes an ignition coil having a primary coil and a secondary coil, a switching element connected between the primary coil and a ground, a battery and a spark plug connected to one end of the secondary coil, an engine abnormal condition detecting device includes a Zener diode connected between the other end of the secondary coil and the ground to allow secondary current flowing in the secondary coil toward the ground, a resistor connected between the secondary coil and the ground to limit the secondary current flowing through the secondary coil to a preset level, a secondary current detecting circuit for detecting an amount of secondary current flowing through the resistor, and an electronic control circuit for determining an abnormal condition of the ignition system with reference to the amount of the secondary current flowing through the resistor.